The present invention relates generally to agricultural tillage implements, and more specifically to adjustable harrow assemblies.
Toothed harrow attachments are commonly mounted behind tillage implements such as field cultivators to level soil and help break up large clods. Several ranks of teeth are supported from a drawbar arrangement, and for accommodating tooth adjustments of the aggressiveness of the harrow, the ranks often are pivotally connected to bracket members attached to drawbars. Such attachments include a relatively large number of components, including numerous nuts, bolts and washers which mount the ranks and connect angle adjusting links. Properly assembling the components and torquing the nuts for maintaining adjustability while eliminating excess looseness in the assembly is a difficult and time-consuming task. The numerous components require a lengthy assembly process and add significant manufacturing costs. Such harrows can also be difficult for the operator to adjust and maintain.
A further problem with the conventional harrow design is providing adequate ground clearance during transport of the attachment. A limited amount of space for the rank-supporting structures and adjusting links often prevents pivoting of the teeth to a retracted position for increasing the clearance.
On harrow attachments having adjustable down-pressure springs on the drawbars, providing a simple and reliable adjustment bolt lock has been a continuing source of difficulty. Conventional latch mechanisms wear heavily because of relative movement between the adjustment screw and the latch. Heavy vibration common in the assembly can also result in loss of desired down-pressure adjustment.
It is therefore an object of the present invention to provide an improved harrow attachment for an agricultural implement. It is a further object to provide such an attachment which overcomes most or all of the aforementioned problems.
It is another object of the invention to provide an improved harrow attachment having adjustable teeth. It is yet another object to provide such an attachment which has fewer components and is less costly and time-consuming to assemble and maintain than at least most previously available adjustable harrow attachments.
It is still another object of the invention to provide an improved harrow attachment having adjustable teeth which can be adjusted to obtain various ground profiles and which can be pivoted to a transport position to increase ground clearance.
It is yet another object of the invention to provide an improved harrow attachment having a simple and reliable down pressure adjustment lock.
In accordance with the above objects, an improved harrow attachment includes several clevis-like mounting castings pivotally connected between two identical flat side sheets by a like number of bolt assemblies. A drag link which pivots the ranks in unison is pinned to the legs of the mounting casting between the sheets by free-floating pins captured between the sheets. The bolt and free-floating pin design eliminates numerous components and makes fabrication and maintenance less expensive and time-consuming. The design also allows the castings to pivot farther and the drag link to tuck and be pinned in a transport position for increased clearance between the teeth and the ground.
The rear mounting casting has a longer clevis structure than the remainder of the castings and serves as a tine angle setting or aggressive stop when a stop pin is inserted through apertures in the plates. The ability to adjust tine angle allows different final soil profiles to be obtained. By increasing tine down-pressure and orienting the tines in a generally vertical position, tough large clods can be sized. Decreasing tine down-pressure and decreasing or flattening the tine angle facilitates high residue flow through the harrow without plugging or bunching.
To retain the down-pressure spring adjustment in the desired position, a short section of apertured square tubing or a casting with a round inner surface and rectangular outer surface is placed over the threaded portion of the bolt. An aperture in the bolt is aligned with the apertures in the tubing or casting, and a spring pin is inserted. The tubing or casting, which is sandwiched between the sides of the spring support legs, prevents rotation of the bolt from the adjusted position.